Centrifugal switch having a weighted arm consisting of a strip of resilient material



Jan. 25, 1966 w o. SAUBY 3,231,697

CENTRIFUGAL SWITCH HAVING A WEIGHTED ARM CONSISTING OF A STRIP OF RESILIENT MATERIAL Filed Feb. 10, 1964 INVENTOR WESLEY O. SAUBY ATTORNEY ;$tat Patent v #3331597 j CENTRIEUGA L HAVING -A WEIGHTED .ARM CONSI'STING 0F A STRIP'OF RESILIENT MAT A Wesley O. Sauby, Minneapolis, Minn;, assignor to Electric Machinery Mfg. Company, Minneapolis, Minn., a 'cor- Filed Feb..10, '1964,TSe r.fNo. 343,805 1 Claim. (Cl.200*8'0) The herein :disclose'd invention relates to *centr'ifugally operated switches and has for an object 'to provide a switch capable of being used as an overload or an underload circuit closer or epener when the speed of the revolub'le member reaches an overload or an under'load-speed.

An object of the invention resides in constructing the switch with a support attachable to the revoluble member and on which the various parts are mounted.

Another object "of the invention resides in providing a switch utilizing switch means having an operating member movable "in a radial direction. g z j A still furfhe'r'dbject 'o'fthe 'inv ntion resides in providing a weighted arm a es in co'njunction with resilient means for moving said operatinggmemb'er to open or close the switch either when the speed of the revoluble member reaches a predetermined high speed-or 'a predetermined low speed. V I v An object of the invention resides in constructing the arm from a strip of resilient material and disposed in a direction transversely of the direction of movement of said operating member and in forming the one end of the arm furthest from the operating member with a bend providing a loop serving as a hinge and as the resilient means for the arm and in providing the outer end of the loop with a flange attached to said support.

Another object of the invention resides in providing the arm with a bend near the end adjacent the switching means forming a weight extending outwardly from said am.

A still further object of the invention resides in providing the support with a hole therein and through which the arm extends and in screwing a screw in the support entering said hole and engaging the arm to limit the initial pressure of the arm on the operating member.

Other objects of the invention reside in the novel construction and arrangement of parts and in the details of construction hereinafter illustrated and/ or described.

Changes in the specific form of the invention as herein described may be made within the scope of what is claimed without departing from the spirit of the invention.

FIG. 1 is a fragmentary elevational view of a portion of an electrical generator illustrating an embodiment of the invention applied thereto.

2 is a fragmentary end view of the structure shown in FIGrl and drawn to a greater scale.

FIG. 3 is a fragmentary sectional view taken on line 33 of FIG. 1 and drawn to the same scale as FIG. 2. FIG. 4 is a sectional view taken on line 44 of FIG. 2 and drawn to the same scale.

FIG. 5 is a fragmentary perspective View of the switch means of the invention with portions cut away to illustrate the construction thereof.

For the purpose of illustrating the invention a portion of a generator has been shown which includes the shaft 11 of the generator. Mounted on the end of the shaft 10 is a disc 26 which is formed with a recess 21 adapted to receive the end 12 of the shaft 11. The disc 26 is attached to the end 12 of said shaft by means of cap screws 32 which extend through hole-s 23 in said disc and are screwed into the end of said shaft. This disc has a number of openings therein of which two openings 24 and 25 have been illustrated.

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Mounted transversely of the upper portion of the opening 24 'is a switch means which includes a case -3.1. Disposed in this case is an overcenter arm '32 which is pivoted at one end by means of a "fulcrum '33 secured to the bottom wall 56 of'said case. A tension-coil spring '35 is hooked at one end 36 to the arm 32 intermediate its ends. This spring operates in a slot "37in saidarm and through which-the spring extends. The other end 380i the spring 'is hooked into a plate 39 attached 'toi'the case .31 by means of a construction not :shown. The arm 32 has contacts on it whichare adapted to engageieither of two contacts 41 or *52 disposed on opposite sides :of said arm. These contacts are connected with-terminals 43 3116144 which extend through theend wall 3 4;ofjthe case angdare acce'ssible for connection,in the cicuit in which the switch meansis used. Another term nal 45 extends .thr'oughthetend ;w11l 46.0f theicase and is connected to the plate 39. For operating the switch anoperatin'g member 57 is employed which i's 'p' ro'v-ided witha shank 48 slidable in a slot 19'inthe wall 51of said case. The said shank 48 terminates in a button 52 a CfiiSSlble from the exterior of the case andhas mounted on .the interior thereof an engaging member 53 adapted toengage'the spring 35. When the spring '35 is pushed one direction by engagement with the button 52, the arm; 32 is moved in a manner 'to cause 'one 6f 'the conta'ct's 'th'ereon to engage the contact-41. When pressure is released on the button 52 spring 35 returns the arm to a position in which the other contact thereon engages the contact 42.

Operating in conjunction with the switch means 30 is a weighted arm '60. This arm is constructed from a strip of bendable spring metal and extends through the opening 24 in the disc 2-6. This arm lies directly inwardly of the button 5-2 and is adapted to engage the same. One end of the arm is bent to form a loop 61 which is formed with a flange 62 extending outwardly therefrom. Screws 63 extend through said flange and are screwed into the outermost portion of the disc 26 to hold the arm 60 attached to said disc. The loop '61 permits of flexing the arm 60 and to move in a radial direction to operate the switch means 30. The arm 60 is bent at its other end to form a portion 64 extending in a radial direction and which serves as a weight together with the weight of the arm itself.

Adjustment of the initial pressure of the arm 60 on the button 52 is procured by means of a screw 65 which is screwed into a threaded opening 66 in the disc 26. This screw is held in adjusted position by means of a lock nut 67. The weight of the arm 60 plus the weight of the I weight 64 are operated by centrifugal force to cause said arm to swing outwardly and to press the button 52 into its operative position within the switch means 30.

In operation the screw 65 is adjusted so that the arm 60 will operate the operating member 47 to open a circuit through the contacts '41 and contact on said arm. A circuit through these contacts may be completed to indicate over speed or a circuit may be embodied which will reduce the speed of the generator shaft.

In conjunction with the opening 25 another switch means may be embodied which is identical to that previously described. For this reason, the illustration and description of the device will not be repeated. It will, however, be readily comprehended that the circuit through the contact 42 and the contact on the arm 32 may be used in a circuit. which would indicate under speed. Again, the circuit m1ght contain indicating means or the same might contain means for increasing the driving speed of the generator.

The terminals 43 and 45 of the switch 20 are connected to brushes 68 and 69 mounted on a bar 71. This bar is attached to a bracket 72 which is secured to the frame of the generator in any suitable manner. Two collector rings 73 and 74 are employed mounted on and insulated from shaft 11 and which are engaged 'by the two brushes 68 and 69.

The advantages of the invention are manifest. The invention can be constructed at an extremely low expense. The parts will not readily get out of order and can be easily adjusted. The construction shown will operate at a higher speed than similar devices now on the market. A switch means, such as illustrated and described, requires but an extremely small movement to operate and the switch can be used where only slight movement of the weighted arm results. The device is extremely compact permitting a number of units to be mounted on the same disc thereby readily increasing the usefulness of the switch. The weight of the switch arm can be varied by increasing or decreasing the size of the weight and/ or by makingthe switch arm of heavier or lighter material.

Having described the invention, what is claimed as new 7 and desired to be protected by Letters Patent is:

'A centrifugal-1y operated switch for attachment to a revoluble member and responsive to the speed of said member, said switch comprising:

, (a) a disc-like support secured to said revoluble member,

(b) said support having a hole therein extending in a direction parallel to the axis of said revoluble member, I I

(c) an arm constructed from a strip of spring material including an outwardly projecting portion extending 4 1 through said hole and projecting outwardly beyond said disc at one end of said hole,

(d) the outwardly projecting portion of said .arm hav ing a par-t bent outwardly therefrom and substantially at right angles therewith and spaced therefrom to form a weight at the end of said arm,

(c) said arm at its opposite end having a bend therein forming a loop substantially semi-circular and disposed outwardly 'beyond said disc at the other end of said hole,

(f) a flange issuing outwardly from said loop, overlying and secured to said disc,

(g) switch means mounted on said disc and disposed in the space between said weight and disc,

(h) said switch means having an operating member engageable with the projecting portion of said arm, and

(i) an adjusting screw screwed into said disc and entering said hole and contacting the portion of said arm within said hole.

References Cited by the Examiner UNITED STATES PATENTS 2,830,205 -4/195-8 Castagna 73-546 XR 3,172,458 3/1965 Smith 200-s0 x 

